Method and apparatus for horizontal drilling and oil recovery

ABSTRACT

An oil tool forms holes or perforations which extend horizontally away from the borehole and into the formation for recovering additional oil and gas from the formation. The tool provides a downhole tool capable of drilling horizontally into a formation and further capable of operating in a relatively small well bore, such as those having a diameter of less than six inches. In addition, the tool does not tend to spiral or otherwise deviate from horizontal during drilling operations. The tool of the present invention includes a drill capable of drilling or tunneling through the formation, a magazine or carrier which contains a plurality of hollow joints or segments, a hydraulic pump and a mechanism for assembling and disassembling the segments. Once in place, the assembly mechanism removably attaches a segment from the magazine to the drill.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is a continuation-in-part of patent application Ser. No.11/079,705 filed Mar. 14, 2005 which is a continuation of co-pendingpatent application Ser. No. 09/954,891, filed Sep. 18, 2001 andprovisional application Ser. No. 60/233,115, filed on Sep. 18, 2000entitled “Method and Apparatus for Horizontal Drilling and OilRecovery.” Priority is claimed from each of the above noted patentapplications which are enclosed in their entirety by reference herein.The invention is generally related to drilling and producing oil fromabandoned wells and is specifically directed to horizontal drilling andperforating such wells.

2. Description of the Prior Art

As oil supplies continue to deplete, the ability to recover additionaloil from existing and/or abandoned well sites or formations becomes ofgreater importance. One method for recovering additional oil and gasfrom a formation is to create holes or perforations which extendhorizontally away from the borehole and into the formation.

There are tools in the industry capable of forming horizontal bores orholes. These can generally be categorized as (1) hydraulic or (2)flexible shaft tools. As shown in U.S. Pat. No. 4,317,492 (Summers),U.S. Pat. No. 5,439,066 (Gipson) and U.S. Pat. No. 5,853,056 (Landers),U.S. Pat. No. 5,934,390 (Uthe), hydraulic fluid can be used to createholes or perforations in oil bearing formations. Typically a hose ortube is passed down the exiting well bore to a point where thehorizontal bore is desired. The hose extends from the surface, where apump provides pressurized hydraulic fluid, such as water, to erode therock or sand surrounding the downhole end of the hose. While somewhateffective in forming holes in the strata surrounding the main bore, thismethod significantly damages the formation, which may hinder additionaloil or gas production.

Many tools, such as that shown in U.S. Pat. No. 4,226,288 (Collin), aswell as those shown in the '056 and '066 patents, provides a flexibleshaft which extends from the surface, down the main bore and then turnsor bends to extend horizontally into the formation, traveling generallyperpendicular to the main bore. While these tools may be suitable foruse in very large well bores, they are not suitable for use in wellshaving smaller bores because the turning radius of the flexible shaft istoo great. Additionally, those tools which turn the entire shaft toprovide rotation of a drill bit do not typically travel perpendicular tothe well bore. The rotation of the shaft creates a downward spiraling ofthe drill bit.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for forming holesor perforations which extend horizontally away from the borehole andinto the formation for recovering additional oil and gas from theformation. The present invention provides a downhole tool capable ofdrilling horizontally into a formation and further capable of operatingin a relatively small well bore, such as those having a diameter of lessthan six inches. In addition, the tool does not tend to spiral orotherwise deviate from horizontal during drilling operations. The toolof the present invention includes a drill capable of drilling ortunneling through the formation, a magazine or carrier which contains aplurality of hollow joints or segments, a hydraulic pump and a mechanismfor assembling and disassembling the segments. Once in place, theassembly mechanism removably attaches a segment from the magazine to thedrill.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of the vertical bore hole, a horizontal borehole and the assembly of the subject invention.

FIG. 2 is similar to FIG. 1 and shows an alternative embodiment.

FIG. 3 is an illustration of a drill bit used in accordance with thesubject invention.

FIG. 4 shows an alternative embodiment for feeding the segments of thesystem in accordance with the subject invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2, the present invention provides a downholetool capable of drilling horizontally into a formation and furthercapable of operating in a relatively small well bore, such as thosehaving a diameter of less than six inches. The well bore 10 isperforated at the opening 12 for accommodating a horizontal drill bit14. The drill bit is mounted on the front end of a magazine segment 16.The well bore 10 serves as a storage cell for a plurality of segments16, forming a magazine 18. As the bit 14 moves horizontally into thestrata, segment 16A will advance out of the wellbore 10. At this pointthe next in line segment 16B will drop into the loading cell 20 andcouple to the next ahead segment 16A, permitting the bit 14 to progressfurther in a horizontal direction. In addition, the tool does not tendto spiral or otherwise deviate from horizontal during drillingoperations. As the drill advances into the formation, the assemblymechanism affixes additional segments, which are fed from the magazine.An alternative embodiment is shown in FIG. 2 and operates in the samemanner as that shown in FIG. 1.

Specifically, the tool of the present invention includes a drill capableof drilling or tunneling through the formation, a magazine or carrierwhich contains a plurality of hollow joints or segments, a hydraulicpump and a mechanism for assembling and disassembling the segments.Initially, the tool is lowered into the bore, down to the desired levelusing known wireline techniques. Once at its destination, the tool maybe removably affixed in the bore using any suitable method or mechanismto prevent movement of the tool during operation. Once in place, theassembly mechanism removably attaches a segment from the magazine to thedrill. Hydraulic fluid from the pump may then be passed through thehollow segment to the drill to power the bit. The drill the travels outof the tool through an opening or aperture therein and into theformation. The pump of the present invention is preferably located inthe tool itself, rather than at the surface. As the drill advances intothe formation, the assembly mechanism affixes additional segments, whichare fed from the magazine, onto the previously attached or assembledsegment. Once the horizontal bore is formed, the drill may be drawn backinto the tool. After completing a horizontal bore, the tool may beraised or lowered for further drilling or may simply be rotated to allowan additional horizontal bore to be formed at the same depth.

Although any suitable drill may be used, as shown in FIG. 3, the drilltypically incorporates a suitable bit 22 and a plurality of drivemechanisms such as the drive wheels or axles 24 disposed on the exteriorof the drill to aid in driving or pushing the bit forward into theformation and to provide stability for the bit during operation.Hydraulic fluid from a pump turns the bit in the manner well known tothose who are skilled in the art and provides power to the drivemechanism. The drive mechanism may include wheels, tracks or any othersuitable device. Preferably, a plurality of tracks are affixed in aspaced manner about the outside of the bit.

The segments preferably have a hexagonal or octagonal shape to addrigidity and prevent bending during drilling. Each segment has a first,leading end and a second, trailing end. The leading end of each segmentcorresponds to the trailing end of the segment before it. In this way,the segments may be removably joined by the assembly mechanism andpassed into the newly formed horizontal bore. For example, correspondingfirst and second ends may be threaded internally and externally,respectively. Corresponding ends may have any suitable interlockingarrangement. The segments have a diameter smaller than that of the holeor bore formed by the drill bit. Preferably, each segment isapproximately three inches in length and may be formed from any suitablematerial, but preferably a metal such as steel. It may be desirable, incertain instances, to include spacers or support devices at spacedintervals along the assembled segments. Such spacers provide support forthe segments and prevent bending of the assembled segments, which mayoccur due to the smaller diameter of the segments relative to thehorizontal bore. Where spacers are used, they are typically slotted toallow fluid and cuttings to pass out of the horizontal bore. Themagazine or carrier may be size contain any number of segments,preferably, however, the carrier accommodates enough segments to allowthe drill to travel approximately forty feet from the main bore.

In a another embodiment, and as shown in FIG. 4, the present inventionis a downhole horizontal drilling tool which includes a drill, a linkedchain drive system and a hydraulic pump. The drill preferably has aplurality of drive mechanisms 24 positioned thereon, as previouslydescribed. Hydraulic fluid from the pump drives the drill bit and drivemechanism.

The linked chain drive system includes at least a pair of pulleys 32,34, one of which may be moved axially within the tool, a linked chain ofsegments 36, and a drive motor 38. Preferably, the linked chain ishollow to allow fluid to pass therethrough. The last segment in thelinked chain is attached to the drill 14. As the drill travels into theformation, the linked chain is pulled into the formation as well. As thelinked chain travels into the formation, an upper, axially moveablepulley 32 travels axially downward, thereby allowing the chain to travelout into the formation while keeping tension in the chain andcontrolling the rate at which it travels. A lower, fixed pulley 34allows the chain to turn out of the tool and into the formation.Additional pulleys may be used to further control the movement of thelinked chain. The motor 38 controls the movement of the upper pulley andmay rotate drill stem 40 inside the linked chain. Alternatively, a pumpmay supply a hydraulic fluid through the chain to turn the drill bit anddrive the drive mechanisms in the manner well known. Once the horizontalbore is formed, the drill and linked chain is drawn back into the tool.

While certain embodiments and features have been disclosed in detailherein, it should be understood the invention includes all enhancementsand modifications within the scope and spirit of the following claims.

1. An apparatus for drilling a horizontal borehole from a verticalwellbore, comprising: a. a drill bit; b. a plurality of hollow segmentsin the vertical wellbore, one of which is attached to the drill bit; andc. means for driving the drill bit through the hollow segments.
 2. Theapparatus of claim 1, wherein the segments are stored in an unattachedmanner within the wellbore and are sequentially attached to one anotheras the drill bit advance horizontally.
 3. The apparatus of claim 2,further including a magazine of stacked segments in the wellbore.
 4. Theapparatus of claim 3, further including a load cell located at aposition in the wellbore at which a horizontal perforation is desired,wherein each segment in the magazine of stacked segments drops into theload cell and is attached to the next adjacent segment as the drill bithorizontally advances.
 5. The apparatus of claim 1, further including adrill stem extending through the segments and attached to the drill bitfor driving the drill.
 6. The apparatus of claim 1, wherein the hollowinterior of the segments form a fluid conduit for hydraulic fluid fordriving the drill bit.
 7. The apparatus of claim 1, wherein the segmentsare connected in a chain and are carried in a loop in the well bore. 8.The apparatus of claim 7, further including a first guide means near thetop of the well bore for supporting and guiding the chain of segmentsinto the wellbore and a second guide means adjacent a location in thewellbore where a horizontal perforation is desired for guiding thesegments into the horizontal perforation.
 9. The apparatus of claim 8,wherein the first guide means is axially movable in the wellbore forkeeping the chain of segments in tension.
 10. The apparatus of claim 8,wherein the guide means is a pulley.
 11. The apparatus of claim 8,wherein the guide means is a sprocket gear designed to engage the chainsegments.